Organic thin films have been produced by various methods such as surface adsorption, vacuum deposition, sputtering, and chemical vapor deposition (CVD) thus far. Particularly, among the surface adsorption methods, the monomolecular build-up process, i.e., the Langmuir-Blodgett (LB) process has attracted special attention as a one capable of providing monomolecular films or multilayered films composed of monomolecular layers. Actually, LB films of many materials such as optically functioning materials (e.g., merocyanine derivatives which are non-linear optical materials, and cyanine dyes and spiropyran derivatives which are optical recording materials) and bio-molecules have been produced. However, such films still await solutions for the problems of film defects and optimization of the molecular structure for use as a practical material. Hence, they are not yet sufficiently reliable for the practical application.
On the other hand, CVD, sputtering, and vacuum deposition processes are conducted under vacuum to thereby avoid incorporation of impurities into the deposited films. Among these processes, the CVD and the sputtering methods involve high energy at the film deposition, and are therefore used for particular cases in which high reaction energy is required at the film deposition and not for the organic materials which decompose at low temperatures in general. With respect to the filming energy, the vacuum deposition method ranks between the sputtering and the surface adsorption method. Though not applicable to materials in which the temperature of sublimation is near to that of decomposition, the vacuum deposition method is useful for depositing films of materials having temperature difference between decomposition and sublimation, and by optimally setting the sublimation temperature, it has successfully provided films of various molecules including those of TCNQ, TTF, phthalocyanine, and stearic acid.